His father was a critic of the Assad regime in Syria and an imam at the An Noor mosque in Acton, west London, from 2005 to 2011.

He was found dead in a car with gunshot wounds on April 7.

Mr Arwani also urged anyone who may be able to help with the investigation to come forward.

He said: "If anyone has any additional information that can help with the investigation, we urge you to please come forward and speak to the Metropolitan Police.

"Your co-operation will help us close this painful page and begin to move on with our lives, in the knowledge that the person who took away our father will be brought to justice and duly punished for this heinous crime."

Earlier today, 36-year-old Leslie Cooper appeared in court charged with Mr Arwani's murder. He did not enter a plea and was remanded in custody to appear at the Old Bailey later this week.

Mr Arwani was speaking as a second man was arrested in connection with his father's murder.

Counter terrorism officers arrested the unnamed 61-year-old on suspicion of conspiracy to commit murder, following the death of Mr Arwani in the Greenhill area of north-west London.

As part of the ongoing investigation, officers are searching addresses in London including areas within the An Noor Cultural and Community Centre in west London.

A police spokesman said: "All officers involved in the search of the mosque are sensitive to the impact that their presence will have and are aware that this action may cause concern in the local community.

"We have been in contact with trusted community Muslim advisers this afternoon to reassure them that the action is necessary and that the premises will re-open as quickly as possible.‪"

A spokesman for the mosque said no one was available to comment.

Prayer mats were temporarily placed outside the building as specialist forensics officers searched the premises into the night.

Two officers stood at the main entrance, while another was positioned around the side. A handful of worshippers waited across the road ahead of evening prayers.